Natural Selection: Natural selection is the process by which certain traits become more or less common in a population over successive generations. It can be compared to a talent show where only the most impressive acts move on to the next round.
Common Ancestor: A common ancestor refers to an organism from which two or more different species have evolved. It's like finding out that you share the same great-great-grandparent with someone you didn't know existed.
Adaptation: Adaptation refers to changes in an organism's physical or behavioral characteristics that help it survive and reproduce in its environment. Think of adaptation as wearing sunglasses on a bright sunny day to protect your eyes from harmful UV rays.